The power semiconductor module is used in a wide power converter field from household electrical appliances, such as home air conditioners and refrigerators, to industrial electrical appliances, such as inverters and servo controllers.
The power semiconductor module is mounted on a direct copper bonding (DCB) substrate or a metal base printed wiring board with a high radiation performance in terms of power consumption. One or more circuit elements, such as power semiconductor elements, are mounted on the wiring board and a plastic case frame (resin case) is bonded to the wiring board. Then, the plastic case frame is sealed with a sealing material such as silicon gel or an epoxy resin. The metal base printed wiring board is one of the printed wiring boards including a copper film for a circuit pattern, a resin insulating layer, and a metal plate. A circuit pattern is formed on the upper surface of the metal base printed wiring board.
In addition, there is a full mold power semiconductor module using a transfer molding method in order to reduce manufacturing costs. In general, the power converter includes a main circuit using the above-mentioned power semiconductor module, a power circuit, and a control circuit. The power circuit or the control circuit includes various components, such as an integrated circuit (IC), a large scale integrated circuit (LSI), a resistor, a capacitor, and a reactor. In general, the power circuit or the control circuit is mounted on a printed circuit board.
Next, a power converter provided with a power semiconductor module 30 according to the related art disclosed in Patent Document 1 will be described.
FIG. 9 is a diagram illustrating the structure of a main portion of a power converter 600 including the power semiconductor module 30 according to the related art. In the power converter 600, the power semiconductor module 30 which includes a power semiconductor element 51 forming a main circuit is mounted on a heat sink 11 (hereinafter, also referred to as a “cooling fin”), with a thermal compound (thermal grease) (not illustrated) interposed therebetween, in order to increase the radiation performance. Printed circuit boards 40a and 40b on which electronic components 60 required for the power circuit or the control circuit other than the main circuit in the power converter 600 are mounted are provided above the power semiconductor module 30 with a gap therebetween and are fixed to the heat sink 11 by supports 70 (for example, pins). Then, all of the structures are covered with a case 50.
Patent Document 2 discloses a power converter having the following structure: a semiconductor device obtained by inserting a radiation plate (metal block) made of, for example, copper into a radiation plate insertion hole of a wiring board that has circuit wires formed on a resin substrate and fixing a semiconductor chip (power semiconductor element) to the upper surface of the radiation plate (metal block) using solder is mounted on a radiator (heat sink), with an insulating layer, which is formed on each of the rear surfaces of the resin substrate and the radiation plate (metal block), interposed therebetween.